Telescopic steering shafts for motor vehicles are known, in which telescopic steering shafts an inner spindle and an outer spindle which is complementary with respect thereto and is arranged coaxially with respect to the inner spindle are provided, which spindles can be telescoped relative to one another. In this way, an adjustable-position steering column can be provided in motor vehicles, by means of which steering column the steering wheel position can be adapted at least in the axial direction of the steering shaft to the respective driver's position, in order correspondingly to improve the ergonomics for the driver of the motor vehicle and therefore driving safety. Furthermore, telescopic steering shafts are known for safety steering columns, in which, in the case of a crash, the shaft yields or shortens, for example by virtue of the fact that the driver comes into contact with the steering wheel and then pushes the steering wheel back together with the steering shaft.
Telescopic steering shafts are used in motor vehicles between the steering gear and the steering column and, in addition to setting the position and crash safety, are also intended to compensate for small changes in the spacing between the steering gear and the steering column which occur, for example, on account of dynamic loads during driving operation as a result of the corresponding twisting of the chassis, but also as a result of movements of the steering gear in a rubber mount. These slight changes in the spacing are also intended to be compensated for by way of the telescopic steering shaft with as little noise as possible and such that they are not discernible to the driver.
In addition to a smooth-running and jolt-free axial adjustment, the steering shaft with the telescopic mechanism is also intended to provide as symmetrical a transmission of the steering torque as possible between the inner spindle and the outer spindle, with the result that the driver firstly cannot determine any difference between a steering lock in one direction and a steering lock in the other direction, and secondly any possible play during the transmission of the torque between the inner spindle and the outer spindle is not perceived by the driver.
In order to prevent the two parts which can be telescoped with respect to one another from sliding apart, in particular, during transport of the shaft which is assembled but has not yet been installed in a motor vehicle and during the actual installation of the shaft into the motor vehicle, pull-out protection means are known for limiting the pulling of the two telescopic parts out from one another. For example, DE 100 2004 009 188 A1 has disclosed an axially adjustable steering spindle, in which an inner tube has an outer spline system which provides a stop of the inner tube with respect to a sleeve which is screwed into the outer tube. As a result, a pull-out protection means or pull-out limiting means is provided.
WO 2010/086269 A1 has disclosed a telescopic shaft, in which the outer tube is sealed with respect to the inner tube by way of a seal.